Method of treating pistons and piston rings to prevent distortion in use



H. C. LEESEBERG.

METHOD OF TREATING PISTONS AND PISTON RINGS TO PREVENT DISTORTION INUSE. APPLICATION FILED APR. 18, 1921.

1,412,288. Patented Apr. 11, 1922.

INVENTIIIR A" UNITED STATES PATENT OFFICE.

HENRY C, LEESEBERG, OF IOSTORIA, OHIO.

METHOD OF TREATING PISTONS AND PISTON RINGS TO PREVENT DISTOMION IN USE.

Specification of Letters Eatent. Patented Apr, 11, 1922,

Application filed April 18, 1921. serial No. 462,390. j

To all whom it may concern:

Be it known that I, HENRY C. LEESEBERG, a citizen oft'he United States,and a resident of Fostoria, county of Seneca, and State of Ohio, havemadean Invention Appertaining to Methods of Treating Pistons and PistonRings to Prevent Distortion in Use; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in theartto which it appertains tomake and use the same, reference being had to the accompanying drawings,and to the characters of reference marked thereon, which form a part ofthis specification. I This invention relates particularly to themanufacture of pistons and piston rings.

in the use of cast iron pistons and. piston rings as heretoforemanufactured, at least so far as I am aware, it is found that they arepractically all subject to Warping more or less, the amount ofdistortion depending largely on the shape of the article and theinternal strains that are set up in the process of cooling, and alsoonthe temperature of the motorin which used and the vibrations and jarsto which subjected during a running of the motor, such warping ordistorting of the piston or rings permitting leakage past the same, aswell understood in the art. It is found that there is no greatdistortion in the castings if they are used in the rough, the warpingaction taking place afterj f metal has been removed from the casting bymachining the various surfaces. To remedy such warping of thecastings'it has been customary to allow them to age or set after amachining operation, which process may take six or eight months,depending almost entirely upon the size of the casting and the accuracythat is required of the part after it has been completed.

Unless this is done the finished parts will change shape and size.

The primary object of my invention is to so treat pistons or pistonrings during the manufacture thereof as to eliminate strains andirregularities therein and to prevent warping and distorting occurringduring use, and also to very materially reduce the time required inmanufacturing articles of this class and treating or aging them toovercome the warping tendencies. It has not been customary, however,with piston ring manufacturers to permit the castings to age after beingmachined, and therefore the rings when used are subject to the warpingand distorting tendency to a much greater extent than would be the caseif allowed to stand and age as is done with other castings when accuratework is desired. It is therefore one of the purposes of my invention toprovide a process of treating rings to eliminate warping and distortingtendencies therein by a method which is simple and rapid to perform andcan be practiced by manufacturers where time is a material object.

The invention is fully described in the following specification and apreferred method of practicing the same in the manufacture of pistonrings is illustrated in the accompanying drawings, in which,

Fig. 1 illustrates a ring as it appears in the first step of theprocess. Fig. 2 shows the ring split. Fig. 3 illustrates the heattreating operations, and Fig. 4 the finished ring after the finalmachining operation.

In the manufacture of a piston ring by my method, it is subjected tofive main steps or operations as follows First. The cast iron ringsafter being cast in the usual way are machined preferably, though notnecessarily, to give them a rough finish on their outer peripheries, aplurality of rings during such operation bein usually mounted side byside on a mandrel.

Second. The next step in the operation consists in transversely slittingthe rings to make them of the split type used in pistons. This operationand the first operation do not diifer from the operations heretoforepracticed in the manufacturing of piston rings.

Third. After the machining and splitting operations the rings arereciprocated or agitated in an oven at a temperature from 300' to 900 F.for about three hours and thenpermitted to cool in the oven and to layfor a day or so. The time of exposure to the heat may be len thenedwithout detriment to the process. n practice it is found preferable tosubject the rings to a temperature of between 600 and 700 F., althoughthis temperature may be varied considerably and very good resultsobtained, the intention being to heat the articles to a temperaturewhich is considerably above that to which they will be subjected in use.In this heating operation the rings are loosely mounted on a holdingmember whichis reciprocated within the oven during the heat treatmentreheat the rin motor usually runs which subjected during use in anengine.

so as to subject the rin as nearly as possible to the motions an jarringactions to means of accomplishing this isillustrated crudely in Fig. 3inwhich 1 designates an oven, 2 a ring carrying member suspended withinthe oven from a;-.crank-shaft 3, the member being a apted to have aplurality of rings loosely mounted thereon whereby a turning of theshaft will' impart a rec procatory movement to the member and rings.Fourth. The next step in the process is to for about three hours at atemperature 0 approximately 400 F., or at about 50 above the temperatureto which subjected when in use, which in the ordinaiy between 300 and350 The rings are then ermitted to cool in the oven the same as be oreand to lay for a day or so. The same oven as employed for the initialheatin may be used and the rings subjected to t e shaking or vibratingaction during the heating.

Fifth. The fina step in the operation is to machine the rings in theusual or any suitable manner to correct any warping or irregularitiesremaining therein after the heating ste castings.

s. It is welfknown in the art that the tendency of cast iron to warp orset-is greatly increased after some of the metal has been removedtherefrom by machining, and where accuracy is required castings must beaged or seasoned after each which process (in each case takes from oneto six months, depending on the size of the subjecting the articles tothe heat treatments as above described, they may be machined that theinvention might repeatedly without causing any perceptible warping ordistorting, and it is therefore apparent that my invention residesprimarily in the heat treatment rather than in the machining operations,as the latter are the same as performed with articles as nowmanufactured. In describing my method I have referred to the differentmachining steps with relation to the heating steps so be fullyunderstood. In practice the average iston ring manufacturer does not paymuc attention to the aging process for the reasons, first, that heusuall is unable to get material fast enough and oes not have time toallow it to lay around for agin and, second, the

. aging requires a great eal of extra space and work, and this meansextra expense. With my process it is possible to accomplish in threedays what, by the old method, would require at least sixty days and beless certain in results.

While I have particularly described my process in'connection with themanufacture of piston rings it will be understood that it will besubstantially the same for the manu- A su jected .After the heattreatments t machining operation,

I have found, however, that after facture of a piston, as a piston afterreceivin the initial machining operation would be to the heating andreheating steps substantially as described in connection with the ringsand reciprocated during such heat treatments, so that the piston duringthe heating would be subjected to approximately the same strains andvibrations as would be present' when reciprocating1 in an engine. pistonis subjected to a final machining o eration to correct any warping orirregu arities therein. Having thus described my invention, what I claimas new and desire to secure by Letters Patent, is,-

1. The method of treating cast iron pistons and pistonringsnto preventwarpingand distortin in use, consisting in subjecting the articles or aperiod to a temperature above the temperature to which subjected in use,then allowing to cool and later reheating the articles in a temperaturegreater than that to which subjected in use and allowing to cool and layfor a period preparatory to finishing to correct war ing andirregularities therein.

2. The metiiod of treating cast iron pistons and piston rings to preventwarping and distorting in use, consisting in subjecting the articles fora period to a temperature above the tem erature to which subjectedinuse, agitatingthe articles while in such temperature, then allowing tocooland later reheating the articles for a period in a temperaturegreater than that to which subjected in use and allowing to cool and layfor a period preparatory to finishing to correct warping andirregularities therein.

3. The method of treating cast iron pisand distorting in use, consistingin sim taneously reciprocating and heating the articles in a temperatureabove that to which the articles are subjected in use andthen allowingto cool.

' 4. The method of treating cast iron pistons and piston rings toprevent warping and distorting in use, consisting in simultaneouslyreciprocating and heating the articles in a temperature above that towhich the articles are subjected in use, then allowing to' cool, andlater simultaneously reciprocating and reheating the articles in atemperature above that to which subjected in use and allowing to cool.

5. The method of treating cast iron pistons and piston rings to preventwarping and distorting in use, consisting in subjecting the articles fora period to a temperature between 300 and 900 F. then allowing to cooland lay for a period, then reheating the articles in a temperaturegreater than the temperature to which subjected in use and then allowingto cool and lay for a period preparatory to finishing to correct warpingand irregularities therein.

catin the articles in b 6. The method of treating cast iron pistons andpiston rings to prevent warping and distorting in use, consisting inreciproan oven for about three hours in a temperature above that towhich subjected in use, then permitting to cool and to lay for a day orso, then reheating the articles for' about three hours in a temperatureabove that to which the articles are subjected in use, and then allowingto cool and lay for a day or 'so preparatory to finishing to correctwarping and irregularities therein.

7. The method oftreating cast iron pistons and piston rings to preventwarping and distorting in use,

consisting 1n reciprocating the articles for about three hours in atemperature between 300 and 900 F. which temperature should be abovethetemperature to which the articles are subjected in use, allowing thearticles to cool and to lay for a period, then reheating the articlesfor a period in a temperature about 50 above the temperature to whichsubjected in use and allowing to cool and lay for a period preparatoryto machine finishing to correct warping and irregularities therein.

In testimony whereof, I have hereunto signed my name to thisspecification.

HENRY o. LEESEBERG.

